Physiological and immunological studies on LH-releasing hormone (LH-RH) and its analogues are in progress. These studies include investigation of localization of LH-RH in the hypothalamus and other area of brain, establishment of radioimmunoassay method for LH-RH in plasma, effects of sex steroids on the pituitary responsiveness to LH-RH and the response pattern of the pituitary to LH-RH and its analogues.